The present invention relates generally to semiconductor devices and more particularly to a clip assembly for attachment to a semiconductor package to electrically short circuit the leads of the package and thereby prevent the buildup of a static charge on the active elements of he semiconductor which might cause damage thereto.
Semiconductor integrated circuits such as MOS and C-MOS circuits are known to be particularly susceptible of damage from very small static electrical charges. Such circuits are normally placed inside an insulating package, usually in the shape of a rectangular solid and are provided with a plurality of leads extending from the sides of the package by means of which electrical connections are made to the circuit. These leads usually extend from the package in a direction susbstantially normal to the major plane thereof and are adapted for insertion into circuit boards for soldering and/or other assembly operations.
The susceptibility of these integrated circuits poses a handling problem particularly in the assembly of the packages onto circuit boards. If a worker's body has accumulated a static charge and the worker picks up an unprotected circuit package, the likelihood of internal damage to the intergrated circuit is very great. Such a damage circut or "chip" is not normally discovered until test after the assembly operation has been completed. If discovery is not made until such time, considerable extra work is reguired to remove the "soldered in place" device and replace it.
Integrated circuits of this nature are often shipped by their manufacturer with their connection pins pressed into a piece of conductive plastic. This quite effectively shorts all the pins together and prevents any static buildup between the circuit elements during shipment. There comes, however, a time when the chip must be removed from the manufacturer's shipping protection for assembly onto the board.
To reduce the possibility of damage through static charge, elaborate measures are taken in the assembly operation. Workers are often required to wear special static-free clothing and work in an atmospherically controlled room. In addition, workbenches are grounded and the workers are sometimes "handcuffed". By handcuffed it is meant that the worker must wear a grounding braclet, when he or she is at his work station, which consists of a snug fitting conductor around each wrist. The braclet is connected by suitable means such as a braided grounding strap to the grounded workbench. When the chips are moved from one work area to another, they are often sealed in foil lined bags. All of these restrictions are, at best, bothersome in that they restrict the worker's mobility and tend to diminish his effectiveness. In addition, such requirements represent considerable extra costs to the assembly operation.
Shorting clips or devices for shorting the several leads of the semiconductor package together are known in the art. Known shorting clips, however, all suffer from one or more of several defects including a structure which does not insure positive registration or electrical contact with each of the leads, a complex structure which must be removed prior to final assembly onto the printed wiring board, a failure to provide a secure and positive registration between the clip and the package and a repositioning of the clip before the chip can be placed on the printed wiring board.